大气气溶胶中碘形态研究进展

大气中的碘直接影响对流层中多种光化学反应并间接影响全球气候变化,因而碘的大气化学机制研究受到越来越多关注.气溶胶中的碘是其大气化学反应的最终产物,通过其赋存形态可以推测和了解碘的大气化学过程.大气碘化学理论一直认为IO3-是大气碘沉降中最主要的碘形态,但近年来的各地实测数据发现大气气溶胶中的碘形态大多以可溶性有机碘或I-为主.这种分歧说明目前的大气碘化学理论尚有待完善.本文详细介绍了近年来碘的大气化学以及气溶胶颗粒物中碘形态的研究进展.     

天津东部地区水土环境碘地球化学特征及其成因分析

碘是人体必需的微量元素之一,高碘或低碘均能引起人类或动物的各种疾病。对天津东部地区水土环境中碘地球化学特征及成因进行了研究,结果表明,研究区表层土壤碘含量变化范围是0.89～17.09 mg/kg,平均为5.11 mg/kg,是天津市背景值的1.92倍,是全国背景值的1.36倍。深层土壤碘含量在0.64～34.55 mg/kg之间,平均为10.73 mg/kg,是天津市深层土壤基准值的3.93倍,是研究区表层土壤的2.1倍,研究区表层和深层土壤碘均处于富集状态。表层土壤碘高背景区分布面积较大,主要集中分布在东丽区、宁河区南部、滨海新区北部。浅层地下水碘含量范围在0.03～4.00 mg/L之间,平均为0.56mg/L,高碘地下水分布面积较大,主要分布在东丽区、津南区、宁河区南部、滨海新区(除去西南部)。研究区历史上海陆交互作用强烈,海水提供的大量碘物质在此残留富集,可能是造成水土环境中碘元素整体偏高的自然原因。     

聚碘树脂─—高效消毒剂

此文介绍聚碘树脂的灭菌作用，讨论灭菌效果，稳定性和耐久性。聚碘树脂适用于井、河、湖水的消毒，其速度快，不需除去消毒剂残渣等特点。     

高碘地下卤水中细菌产碘氧化酶的影响因素

高碘地下卤水的细菌碘氧化过程可以减轻工艺管线的生物污损危害。分离自高碘地下卤水中的细菌Roseovarius sp.IOB-7,其分泌的碘氧化酶可催化氧化碘离子生成能够抑制敏感菌生长的碘单质,从而减少生物污损。实验结果显示,加入16μmol/L的Cu~(2+)可促进IOB-7的生长,并将碘氧化酶活力提高了1.75倍。碘氧化酶的最适反应温度为50℃,最适pH为5.5。以碘离子为底物的催化氧化反应中,当pH值为9时,Trametes versicolor漆酶已经完全失活,而碘氧化酶则仍然保持了32%的相对酶活力,显示出更好的pH应用范围和稳定性。开展高碘地下卤水环境中细菌碘氧化酶的研究,对利用生物酶法进行工艺管线生物污损的防治有积极的指导意义。     

碘离子选择性电极测定海带浸泡水中痕量碘

海带浸泡水中含碘大约300-500ppm,经过离子交换提碘后的废水中仍有痕量碘,其量一般在10ppm以下。目前测定痕量碘的方法,通常溴水氧化法(1)。这种方法繁琐、准确度不高,且溴水还会影响人的健康。 我们尝试了用碘离子选择电极测定海带浸泡水中的痕量碘。此法简单,快速、灵敏度     

有待开发的补碘食物

有待开发的补碘食物碘，是人体所必需的一种微量元素，适量的破能维护人体的健康，保证儿童、少年智力的正常发ｔ了。｝．、一旦缺碘。就会患上“碘缺乏病”（简称ＩＤＤ）．成军｝’ｗ缺碘患甲状腺肿病，婴幼儿患克汀病。据有关资料报道，我国现有４亿多人生活在碘缺乏区...     

碘与甲状腺偶发病

甲状腺偶发病是一种亚临床甲状腺疾病，为无临床症状的甲状腺小结或甲状腺肿，常被忽视或被过度重视而作不必要的处理。1发生率甲状腺小结或甲状腺肿的发生率具高度的地区性，特别与碘供应状态相关。在富碘地区，4％～7％成年人可发现甲状腺小结。检查甲状腺小结可以发现早期甲状腺癌，据报告，在有显性甲状腺小结的妇女癌变率高达4．1％～17％，在男性为8．2％～13％，在有多发性小结的患者为4．1％～13％。在缺碘地区，约一半有给节性甲状腺异常患者有癌瘤，而在富碘地区此类患者的癌变率仅为5．3％。早已有资料表明，隐性甲状腺小结可见…     

环境中碘的分布与迁移

前言碘是人类必须的元素,在体内甲状腺对碘的浓缩,起了重要的作用。大家知道,大陆的内陆和山地等,碘浓度低的区域甲状腺肿的发病率很高,为此,对环境     

土壤焙烧过程中碘的释放及其环境意义

研究了温度和焙烧时间对黄壤和红壤碘排放的影响。随着焙烧时间的增加,土壤中碘的逸出率呈上升趋势,900℃时焙烧90min后碘的排放基本达到平衡。土壤中的碘主要以吸附形式存在,各种吸附剂对碘的吸附强度不同,从105℃开始即有部分碘被释放出来,随着温度的升高,更多的碘被解吸、释放。焙烧90分钟,1100℃时碘的逸出基本达到平衡,红壤和黄壤碘的逸出率分别为99.85%和98.52%。500℃和900℃左右是土壤碘释放的两个高峰,分别对应着高岭石和蒙脱石的脱羟基作用,这表明有相当一部分I-取代粘土矿物晶格中的OH-而进入了晶格内部。粘土砖生产过程中碘的排放系数约为97.56%,通过计算得出我国粘土砖生产每年向空气中排放4100t碘,其对生态环境与人体健康有重要影响。     

催化反应－XRF测定痕量碘的研究

基于在稀硫酸介质中，碘对Ｃｅ（Ⅳ）氧化Ａｓ（Ⅲ）的反应，建立催化动力学－Ｘ射线荧光光谱（ＸＲＦ）法测定痕量碘．该法线性范围为０一２μｇ／２０ｍＬ，检测限为０．０２μｇ／２０ｍＬ．     

环境中的碘与地方性甲状腺肿

本文从医学地理观点论述环境中的碘与地方性甲状腺肿地理流行的关系,提出了饮用水的碘含量与地方性甲状腺肿患病率的相关模式、我国地方性甲状腺肿病病区的成因类型及生产化预防措施.     

离子色谱法测定水中碘化物

建立了以AS19阴离子交换分离柱,KOH淋洗液自动发生器,抑制型电导检测器测定水中碘离子的离子色谱方法,优化了色谱条件,结果表明方法不受F-、C1-、NO2-、NO3-、PO42+、SO42-干扰,检出限为0.001 mg· L-1,线性范围在0.001 mg· L-1～1.000 mg· L-1,相关系数R2=1,精密度高,准确度好.     

大气对人体硒、碘、氟的直接影响研究

对一个磷肥厂周围12个村庄的人发、粮食和饮水硒、碘、氟进行了测定,利用改进的模糊数学中的群体识别法对以上数据进行分析,所得结果表明,受污染较重的几个村庄人体硒、碘、氟含量确实受到来自磷肥厂的大气高浓度硒、碘、氟的直接影响.     

我国降水、降尘中硒、碘、氟的研究

研究了我国东甫沿海至西北地区降水、降尘中硒、碘、氟的分布及其影响因素,结果表明。我国降水硒、碘、氟含量范围分别为0.03—0.59ppb、0.3—3.8ppb和0.03—0.6ppm,一般为0.1—0.2ppb、1—2ppb和0.05—0.1ppm,其主要影响因素为人类活动,海洋、风沙及土壤微生物亦各有不同程度的影响。以集尘桶采集的降尘硒、碘、氟含量均远高于当地表层土壤,主要受当地大气污染状况、降尘量、降水量及降水中该元素含量的影响。硒、碘、氟三元素的挥发性与水迁移性的相互关系在很大程度上决定着我国四大地方病的分布。     

上海市饮用水中微量元素碘含量的检测与分析

碘元素是人和动物所必需的微量营养元素。饮用水中的碘含量与人类生活息息相关。通过检测上海市饮用水中碘的含量,探讨碘元素与人体微量元素需要量的关系,为人体适量碘元素摄入和碘相关疾病的防治提供一定的依据。本实验运用催化光度法检测饮用水样品中的碘含量。结果显示:上海市各供水区域饮用水碘化物含量范围在(4.87±1.10)~(8.45±2.36)μg/L(闵行地区样本碘元素含量最高,为8.45±2.36μg/L,而市北地区样本含量最低,为4.87±1.10μg/L);上海市居民经常选择的包装水中,碘化物含量范围在(6.75±0.05)~(10.63±0.03)μg/L(农夫山泉样本碘含量最高,为10.63±0.03μg/L,而康师傅样本碘含量最低,为(6.75±0.05)μg/L),普遍高于上海市自来水的碘含量。通过实验数据分析,上海市饮用水中碘含量处于安全值范围以内,并且远低于饮用水中高碘值150μg/L。     

微量元素碘对儿童身心发育影响的研究

本文研究结果表明,在自然环境缺碘地区持续投放含碘浓度25ppm 的“NaCLI—固”后出生的儿童身高体重发育水平接近对照地区的中等水平;缺碘地区儿童甲状腺激素 T_4、T_3、T_4/T_3比值均在正常范围,甲状腺功能状态基本正常,提示机体内环境缺碘程度已得到纠正;缺碘区儿童 IQ 低下检出率明显高于对照区,血清 Zn 水平则无显著性差异,表明这部分低智儿童与在胚胎期间碘元素相对缺乏有着密切关系.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.